Rating:
After opening and analysing the given elf file, I got a code thats printing flag if all
the given statements gets true else it prints false.
```
__int64 __fastcall main(int a1, char **a2, char **a3)
{
__int64 result; // rax
char *s; // [rsp+28h] [rbp-8h]
if ( a1 == 2 )
{
s = a2[1];
if ( strlen(s) == 34
&& s[3] + s[4] + s[1] + s[7] - s[8] * s[2] * s[6] * s[5] - s[11] - s[9] - s[10] == -52316790
&& s[3] - s[4] - s[6] + s[9] + s[8] * s[11] * s[10] - s[2] + s[5] + s[7] * s[12] == 285707
&& s[11] + s[10] * s[4] + s[3] - s[12] * s[7] - s[13] - s[5] * s[9] * s[6] + s[8] == -797145
&& s[4] + s[12] - s[7] * s[11] - s[9] - s[5] * s[6] - s[14] - s[8] * s[13] * s[10] == -289275
&& s[13] + s[14] + s[7] + s[6] - s[12] - s[15] * s[11] - s[5] + s[8] * s[10] * s[9] == 666868
&& s[12] + s[15] * s[16] + s[11] + s[13] - s[10] + s[6] * s[8] - s[7] - s[9] + s[14] == 9837
&& s[7] + s[11] - s[8] + s[16] * s[13] - s[17] - s[14] - s[9] + s[10] * s[15] - s[12] == 9858
&& s[17] + s[12] + s[9] - s[18] - s[8] - s[15] + s[16] + s[11] * s[14] * s[13] - s[10] == 296504
&& s[11] * s[13] * s[18] * s[16] - s[17] - s[10] + s[9] + s[15] * s[12] - s[19] - s[14] == 10963387
&& s[17] + s[16] + s[20] + s[12] - s[14] * s[18] * s[15] * s[19] - s[13] - s[11] - s[10] == -65889660
&& s[16] - s[19] - s[15] + s[11] * s[13] + s[18] + s[21] * s[12] + s[14] + s[17] * s[20] == 13340
&& s[18] * s[16] + s[17] * s[15] - s[20] - s[12] - s[19] * s[14] + s[22] + s[13] * s[21] == 4641
&& s[15] + s[20] + s[18] + s[21] + s[13] * s[19] - s[22] - s[16] - s[14] + s[17] * s[23] == 6428
&& s[19] * s[24] + s[15] * s[20] + s[16] * s[14] + s[23] - s[18] * s[21] - s[22] * s[17] == 7851
&& s[19] + s[24] + s[22] + s[21] + s[25] + s[16] + s[18] + s[20] * s[23] - s[15] + s[17] == 2997
&& s[17] * s[23] + s[20] * s[25] - s[16] + s[26] * s[21] - s[24] + s[22] * s[19] * s[18] == 342425
&& s[20] + s[26] + s[24] * s[17] + s[27] * s[22] * s[25] - s[21] - s[19] * s[18] + s[23] == 243251
&& s[24] + s[22] + s[25] * s[21] - s[28] - s[19] - s[26] * s[27] * s[20] - s[23] + s[18] == -434772
&& s[28] + s[19] + s[25] + s[29] - s[24] - s[21] - s[23] + s[27] - s[22] * s[26] + s[20] == -4957
&& s[21] + s[30] + s[26] + s[22] * s[23] - s[29] + s[20] - s[24] * s[25] - s[27] - s[28] == -1625
&& s[22] + s[26] + s[25] + s[30] + s[23] - s[24] - s[29] - s[31] - s[21] - s[27] - s[28] == -144
&& s[29] + s[30] + s[31] - s[26] - s[25] - s[23] - s[28] - s[27] - s[22] - s[32] * s[24] == -7001
&& s[33] + s[25] - s[31] * s[23] + s[27] - s[26] * s[32] + s[30] - s[24] * s[29] - s[28] == -18763 )
{
printf("CORRECT :)");
}
else
{
printf("INCORRECT :(");
}
result = 0LL;
}
else
{
printf("Usage: %s <FLAG>", *a2);
result = 1LL;
}
return result;
}
```
Ofc, Simplest approach to this chall will be using z3, code is given below!
```
from z3 import *
FLAG_LEN = 34 s = [BitVec(f's{i}',8) for i in range(34)]
d = Solver() for i in range(10,33):
d.add(s[i] >= ord('0'),s[i]<=ord('z'))
d.add(s[0] == ord('V'))
d.add(s[1] == ord('i'))
d.add(s[2] == ord('s'))
d.add(s[3] == ord('h'))
d.add(s[4] == ord('w'))
d.add(s[5] == ord('a'))
d.add(s[6] == ord('C'))
d.add(s[7] == ord('T'))
d.add(s[8] == ord('F'))
d.add(s[9] == ord('{'))
d.add(s[33] == ord('}'))
d.add(s[3] + s[4] + s[1] + s[7] - s[8] * s[2] * s[6] * s[5] - s[11] - s[9] - s[10] == -52316790)
d.add(s[3] - s[4] - s[6] + s[9] + s[8] * s[11] * s[10] - s[2] + s[5] + s[7] * s[12] == 285707)
d.add(s[11] + s[10] * s[4] + s[3] - s[12] * s[7] - s[13] - s[5] * s[9] * s[6] + s[8] == -797145)
```
From this you will get the Flag,
```FLAG: VishwaCTF{N3V3r_60NN4_61V3_Y0U_UP}```
